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991.
Ho H. Lee Benjamin D. Dickson Ralph J. Stevenson Shangjin Yang Moana Tercel 《Tetrahedron》2019,75(22):3001-3007
An optimised synthesis of a hypoxia-activated anticancer prodrug related to the duocarmycin family of natural products is described. The improved 10-step synthesis increases the overall yield from 4.4% to over 40% while requiring just 2 chromatography-based purifications. The most significant improvements optimise the isomer distribution in a key chlorosulfonylation reaction, and facilitate the removal of tin residues from a tributyltin hydride-mediated radical reaction. Improved preparations of two side chains are also reported. The new method provides practical access to sufficient material to support advanced efficacy and toxicology assessments. 相似文献
992.
We study the free surface of a turbulent channel flow, in particular, the relation between the statistical properties of the wrinkled surface and those of the velocity field beneath it. For an irregular flow shed off a vertical cylinder, surface indentations are strongly correlated with vortices in the subsurface flow. For fully developed turbulence this correlation is dramatically reduced. This is because the large eddies excite random capillary-gravity waves that travel in all directions across the surface. Both their predominant wavelength and their anisotropy are determined by the subsurface turbulence. 相似文献
993.
Cunningham CH Chen AP Lustig M Hargreaves BA Lupo J Xu D Kurhanewicz J Hurd RE Pauly JM Nelson SJ Vigneron DB 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,193(1):139-146
Dynamic nuclear polarization and dissolution of a 13C-labeled substrate enables the dynamic imaging of cellular metabolism. Spectroscopic information is typically acquired, making the acquisition of dynamic volumetric data a challenge. To enable rapid volumetric imaging, a spectral-spatial excitation pulse was designed to excite a single line of the carbon spectrum. With only a single resonance present in the signal, an echo-planar readout trajectory could be used to resolve spatial information, giving full volume coverage of 32 × 32 × 16 voxels every 3.5 s. This high frame rate was used to measure the different lactate dynamics in different tissues in a normal rat model and a mouse model of prostate cancer. 相似文献
994.
The theorem relating the bisectors of the edges of a triangle and the corresponding circumscribing circle is established as a special case of a theorem for triangles with weighted vertices where the edges are partitioned with circular arcs in the proportions of the weights. The circular arcs are established as being uniquely determined by the weights and the triangle, and are given by three circles with collinear centres. These circles either intersect in zero, one or two real points, these latter points being the triple points. 相似文献
995.
In the presence of low‐molecular‐weight organic acids, such as formic, acetic, and propionic, inorganic nickel salts in aqueous solutions are converted to the volatile tetracarbonyl by UV irradiation. Experiments were performed using a flow‐through photoreactor, consisting of a 6 m length polytetrafluoroethylene tubing wrapped around a low‐pressure mercury vapor UV lamp (254 nm, 15 W). The efficiency of transformation was estimated to be 95%. As no carbon monoxide or external reductant is required, photochemical synthesis may prove to be useful in material chemistry and applicable to the extractive metallurgy of nickel, as well as its refining and recycling. Copyright © 2004 Crown in the right of Canada. Published by John Wiley & Sons, Ltd. 相似文献
996.
P. Dawson G. Duggan H.I. Ralph K. Woodbridge G.W. t Hooft 《Superlattices and Microstructures》1985,1(3):231-235
We have combined measured 5K excitonic absorption peaks with calculations of the confined particle states to determine the band offsets in GaAs(AlGa)As quantum well heterostructures. Our observations are best fitted with a conduction band-valence band split of about 75:25. This contrasts with the currently accepted value of 85:15 and the recently proposed value of 60:40. 相似文献
997.
998.
Ralph McKenzie 《Algebra Universalis》1991,28(4):589-603
We prove that in a locally finite variety with the congruence extension property, locally solvable congruences are central and locally solvable algebras are Hamiltonian. Also, we prove that a maximal subuniverse of a finite algebra in an Abelian variety is identical with an equivalence class of some congruence.Presented by H. P. Gumm. 相似文献
999.
Merrick R. Mahoney Martin W. Howard Ralph P. Cooney 《Journal of Electroanalytical Chemistry》1984,161(1):163-167
Weak Raman spectra of carbon monoxide on silver electrode surfaces exhibit frequency and intensity variations with changing potential. The frequency-potential dependence is rationalized in terms of electron-transfer to the antibonding π* state of electrosorbed CO. 相似文献
1000.
Ralph Howard 《Journal d'Analyse Mathématique》1986,47(1):243-253
LetE
n
be a completen-dimensional Riemannian manifold and letM
p
andN
n−p−1
be compact oriented submanifolds ofE
n
whcih are linked inE
n
. The problem (generalizing one due to Gehring whenE
n
is Euclidean) of finding sharp lower bounds on the volume ofM
p
in terms of a lower bound on the distance ofM
p
fromN is solved in (among other cases) the case whereE
n
orM
p
is simply connected andE
n
is a space form or has a nonpositive upper bound on its sectional curvatures. The main technical tool is a generalization
of an isoperimetric inequality of Bombieri and Simon which they used to solve Gehring's problem.
Research supported in part by a Grant from the University of South Carolina. 相似文献